The current sprint looks like another hint the devs don't know what they were doing with the 6.1 update. It's probably supposed to be a QoL, but it's very powerful and the right way to use it is to use it more or less every time. From a simple UX point of view, it's laughable (imagine any other game where the character slows down when attacking, and the player has to push a key to get back to normal speed)

If the devs care, I wouldn't be surprised if they update it to : sprint activate automatically after 5s without action + Bolt reintroduced for on-demand sprint with a cooldown.